The present invention relates to a device for monitoring electrical strikes and, more particularly, to a device which will produce a disturbed magnetic signal directly proportional to the maximum intensity of the lightning strike.
Heretofore, magnetic links were used in monitoring the intensity of lightning strikes and for recording the maximum current amplitudes produced thereby in electrically conductive members. The magnetic links are relatively small links of cobalt steel having a high magnetic retentivity that are magnetically polarized when current passes close thereto. These links are then taken to a laboratory and the degree of magnetization is measured for determining the maximum current that passes thereby.
One of the problems encountered in utilizing such magnetic links is that when two or more strokes of lightning of reverse polarities struck the tower, the residual magnetism produced in the magnetic links would effectively cancel out and indicate a current reading close to zero.
Another problem encountered in utilizing such magnetic links is that high currents from strong lightning strikes would often saturate the magnetic links and provide an inaccurate measurement of the true maximum current.
Another disadvantage in using the magnetic links is that they must be removed and taken to a laboratory for analysis in order to determine the maximum current produced by the lightning strikes.
In U.S. Pat. No. 3,889,185 entitled "Lightning Current Measuring System," there is disclosed a system for monitoring and analyzing electrical currents produced by lightning strikes. This apparatus includes an electrically conductive mass having a first circuit coupled thereto for generating a D.C. voltage proportion to a peak current generated in the mast by each lightning strike. A second circuit is coupled to the mast for generating a digital signal representative of the wave shape of the current generated in the mast by each lightning strike and a third circuit is provided closely adjacent the mast for producing a reference voltage. Signals are fed into a strip chart recorder making a permanent record of the current produced by the lightning strike. Loop antennae are often utilized for determining the distance to a lightning strike from a particular station, and an example of such a device is disclosed in U.S. Pat. No. 3,715,660.